Physical Quantities and Measurement Test - 9

A base quantity is one of a conventionally chosen subset of physical quantities, where no quantity in the subset can be expressed in terms of the others. There are seven basic fundamental quantities: Length, mass, time, electric current, amount of substance, luminous intensity and temperature. So, the base quantity among the following is length.

Mass of steel rod m = 4 kg

Density of steel rod   d = 5896 kg/m³

Volume of steel rod V = m/d

1 pascal (or 1 Pa ) is expressed in other \(\mathrm{Sl}\) units as \(\mathrm{kgm}^{-1} \mathrm{s}^{-2}\)

Magnetic Flux is defined as the number of magnetic field lines passing through a given closed surface. It gives the measurement of the total magnetic field that passes through a given surface area. S.I. unit of magnetic flux is Weber (Wb).

Initial level in the measuring jar Vi= 50 cm3

Final level in the measuring jar V_f = 70 cm3

So, volume of the stone V_stone = V_f − V_i = 70 – 50 = 20 cm³

⟹V_stone=20 cm³= 20 ml = 20/1000litre = 0.02 litre

Electron volt, kilo Watt hour and Watt sec are the units of energy but volt is the unit of potential difference (or voltage). Units of potential difference are joules per coulomb, given the name volt (V) after Alessandro Volta. The familiar term voltage is the common name for potential difference. Keep in mind that whenever a voltage is quoted, it is understood to be the potential difference between two points.

Thus volt is odd one out here.

Light year is the unit of length (distance) while others are unit of time. A light year is a way of measuring distance. That doesn't make much sense because "light year" contains the word "year," which is normally a unit of time. Even so, light years measure distance. You are used to measuring distances in either inches/feet/miles or centimeters/meters/kilometers, depending on where you live.

A Burette  is a device used in analytical chemistry for the dispensing of variable, measured amounts of a chemical solution. A volumetric burette delivers measured volumes of liquid. At its most basic level, volume is simply a measure of space. When measuring the volume of a liquid, sometimes referred to as capacity, the units liters (L) and milliliters (mL) are used. Devices used for this measurement include graduated cylinders, beakers, and Erlenmeyer flasks.

One Femto is a very small unit.

11 Femto =10⁻¹⁵

Density is mass per unit volume. So we need mass and volume to calculate density,

Now for rectangular block the volume is lbh, so we need length, width and height. All the quantities are required.

According to the standard conversions,  1 nm = 10⁻⁹ m

One nanometer is very small unit. of distance.

Percentage error in radius is given as \(2 \%\) i.e. \(\frac{\Delta r}{r} \times 100=2 \%\)

Volume of sphere \(V=\frac{4 \pi}{3} r^{3}\)

Percentage error in volume \(\frac{\Delta V}{V} \times 100=3 \times \frac{\Delta r}{r} \times 100=3 \times 2=6 \%\)

Solar constant \(=G=\sigma T^{4}\left[\frac{4 \pi R^{2}}{4 \pi O^{2}}\right]\)

\(\therefore\) change of \(\mathrm{G}\) w.r.t \(\mathrm{O}\) on both sides

\(\Delta G=4 \sigma T^{3} \triangle T\left[\frac{4 \pi R^{2}}{4 \pi O^{2}}\right]\)

\(\frac{\Delta G}{G}=\frac{4 \triangle T}{T}=-4 \%\)

Current II flow in the circular loop of area a then , magnetic moment will be M = Ia = Am²

The unit for magnetic moment is not a base unit in the International System of Units (SI) and it can be represented in more than one way. For example, in the current loop definition, the area is measured in square meters and is measured in amperes, so the magnetic moment is measured in ampere–square meters (Am²).

The S.I. unit of temperature as per the International System of Units is Kelvin which is represented by the symbol K. The Kelvin scale is widely accepted or used in the field of science and engineering.